Fuel injection device for internalcombustion engines



Mamh 1954 c. G. FAGERHOLT FUEL INJECTION DEVICE FOR INTERNAL-COMBUSTION ENGINES Filed Jan. 18, 1951 attorney- Patented Mar. 2, 1954 FUEL INJECTION DEVICE'FOR INTERNAL- Y COMBUSTION- ENGINES, I

Carl Gustaf Fagerholt, Goteborg, Sweden, as-

signor to Aktiebolaget Volvo, Goteborg, Sweden, .q a corporation of Sweden I Application January 18, 1951 Serial No. 206,704

Claims priority, application Sweden January 21, 1950 2 Claims. 1

The invention relates to. fuel injection devices for internal combustion engines and has for its object to provide in such devices for interrupted injection.

One embodiment will be described in the following with reference to the accompanying drawing which shows a section through a fuel injection pump according tothe invention.

In the drawing I denotesthe housing of the pump and 2 a coupling piece for connecting a feed line to the motor cylinder into which the fuel is to be injected. In the housing is inserted a cylinder liner 3 for a fuel piston 4. The liner 3 is held in place by a stop screw 30. The piston 4 has a plane outer end 3I and at some distance from that end has a circumferential groove 5 formed with a bevelled helical face 6, the object of which is to control the amount of fuel injected by rotating the piston 4. The rotation of the piston 4 is effected by movement of a toothed rack member I cooperating with a toothed segment on a sleeve 8 surrounding the cylinder liner 3. The piston 4 nearer the inner end thereof has projecting portions 32 slidable in slots 33 in the sleeve 8, so that rotation of the sleeve 8 by means of the rack member I also serves to rotate the piston 4. Fuel is supplied from the circumferential groove 34 in the housing and when the piston 4 is in the position shown in the drawing enters the space 35 above the piston. On the pressure stroke of the piston 4 the fuel from the space 35 passes through a non-return valve I0 actuated by a spring 9. When the face 6 reaches the opening communicating with the groove 34 the fuel under pressure in the space 35 is returned through a passage (not shown in the drawing) in the cylindrical surface of the piston 4 to the groove 6 and from there to the groove 34, and by rotating the piston in the manner described by means of the rack member I the amount of fuel thus returned can be controlled and thus also the amount injected.

A spring 28 is compressed between an upper and a lower washer 36 and 29 respectively. The upper washer rests against a seat in the pump housing and the lower washer against a flange I8 on the inner end of the piston 4. The spring 28 serves to return the piston 4 after the pressure stroke thereof.

So far the device described for injecting the fuel and for controlling the amount of fuel injected is known and does not form part of the invention.

The piston 4 is actuated by a cam I I (actuator) on a cam shaft I2. Between the cam I I and the 2. piston 4 is provided a piston plunger for actuatin the piston in response to the rotation of the cam. The piston plunger comprises two essential parts, a sleeve I3 and, a dash piston I6. The sleeve I3 is movable in a bore I4 in the pump housing and is closed by a cross wall 24 fixed therein and carrying on the inside an abutment 2'! andonthe outside a roller I5 for cooperation with the cam I I. The dash piston I6 with the sleeve I 3 and the cross wall 24 forms a closed space 2.3 and is movable in the sleeve I3 between positions determined in one direction by an inturned flange 22 on the sleeve I3 and in the other direction by the abutment 21 on the cross wall 24. The dash piston I6 engages with the inner end of the fuel piston 4 by means of a tappet screw I! screwed iiito the dash piston. The tappet screw is adjustable for length in the known way and is locked in position by means of a lock nut I 9. The sleeve has two openings 20 and 25 for cooperation with passages 2| and 26 respectively in the pump housing I.

3! denotes a plug carrying an oil drenched felt pad 38 for lubricating the cam I I.

In the position shown in the drawing the space 23 is in communication with the passage 2I which contains fluid under pressure, for example oil. The pressure of the fluid is such as to hold the dash piston I6 in the upper position shown in the drawing against the pressure of the spring 28. On rotation of the cam shaft [2 the cam II lifts the sleeve I3, the latter in its turn, owing to the presence of the pressure fluid in the space 23 taking with it the dash piston I6. When the opening 25 in the sleeve I3 reaches the opening leading to the exit passage 26 the fluid in the space 23 suddenly escapes and the movement of the dash piston I6 momentarily ceases until, on continued movement of the sleeve I3, the abutment 21 is brought into engagement with the inside of the dash piston and moves the latter to its uppermost position. During the continued movement of the cam II from its upper to its lower position in the figure the fuel piston 4 is provides for an interrupted injection of the fuel.

Other modifications are of course possible within the scope of the appended claims.

What I claim is: p r

1. Fuel injection device for internal combustion engines, comprising in combination a housing, a cylinder in the housing, a fuel piston movable in the cylinder, means for supplying fuel to the cylinder to the pressure side of the piston, an actuator for effecting the pressure stroke of the piston, means for returning the piston after the pressure stroke, a piston plunger acting between the fuel piston and the actuator and comprising a sleeve having a cross wall and a dash piston movable in the sleeve and forming with the sleeve and the cross wall thereof a confined space, means for supplying fluid under pressure to the confined space at the end of the return stroke of the fuel piston, and means for permitting escape of the fluid from the confined space during the pressure stroke of the fuel piston,

thereby to cause a sudden reduction in length of the piston plunger.

2. Fuel injection device for internal combustion engines, comprising in combination a housing, a cylinder in the housing, a fuel piston mov able in the cylinder, means for supplying fuel to the cylinder tov the pressure side of the fuel 0nd cylinder in the housing between the fuel piston and the actuator and coaxial with the fuel piston cylinder, a sleeve movable in the second cylinder, adapted to cooperate with the actuator and closed by a cross wall, a dash piston movable in the sleeve adapted to cooperate with the fuel piston and forming with the sleeve and the cross wall thereof a confined space, openings in the wall of the sleeve leading to the confined space, a passage in the housing for delivering fluid under pressure communicating with one of the openings in the wall of the sleeve at the end of the return stroke of the fuel piston so as to admit pressure fluid to the confined space and thereby hold the dash piston at a distance from the cross wall, and a passage in the housing for receiving fluid communicating with the other piston, an actuator for effecting the pressure opening in the sleeve when the latter is actuated by the actuator during'the pressure stroke of the fuel piston for escape of fluid from the confined space for suddenly reducing the distance between the dash piston and the cross wall and thereby cause interruption of the injection of the fuel. CARL GUSTAF FAGERHOLT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,033,579 Koster et al. Mar. 10, 1936 2,041,468 Grubbs May 19, 1936 2,046,491 Scott July 7, 1936 

